Open top containers are often used to transport materials, such as fungible goods, by water, rail or road. Open top containers are conventionally covered after loading to protect the container's contents. Such containers may also be covered when empty after unloading for a variety of reasons. During transport and storage, the contents of such open top containers are subject to weather damage and loss from wind.
Open top containers are often used to haul materials such as waste materials, soil, gravel, harvested product, e.g., oats, corn, barley, and wheat, between two or more locations, e.g., fields, silos, processing plants, etc. Typically, such open top containers are loaded from the top which requires a large portion of the top of a trailer to be open for loading. After loading, manually covering the container is time consuming, expensive, and potentially difficult. For example, the installation of a manual tarp over an open top container may take up to 30 minutes. Also, the operator may be required to climb to the top of a container in order to properly attach the tarp and cover the load, which may be inconvenient or difficult.
Several types of tarp systems have been developed to cover open top containers. Cable-pulley systems pull the tarp along a cable system running lengthwise at the top of the container. With such systems, it may take a long time to cover or uncover the container taking into account the typically long length of such containers. Also, with such systems, a cable-pulley often stores the tarp at the front of the container when open, which reduces the open area for loading. Further, the function of such systems can be impeded by large heaped, i.e., fully or over loaded, loads when covering or uncovering the container, which requires more operational time and can increase the difficulty of covering the container.
Another type of conventionally employed tarp system is a flip tarp system, which includes arms on both sides of the container. Such systems generally include arms which pivot about the midpoint of the container body and deploy a tarp over the top of the container as the arms are moved in a forward to rear direction, relative to the container. Such systems typically require a large amount of clearance over the top of the container to keep the tarp from striking any object or obstruction in the path of the arms and tarp.
Another conventional type of tarping system is a side flip tarp system that has arms on at least the front and back of the trailer that pivot at one side of the top the trailer and include a mechanism that moves one or both arms to flip the tarp from a closed position horizontal to the ground to a vertical position alongside the trailer (i.e., parallel to the sidewall of the container). There are also conventional side flip systems where the tarp is split longitudinally into two sections that each have an arms in the front and back of the trailer that pivot at each side of the top of the trailer and include a mechanism to move each section of tarp from a closed position horizontal to the ground to a vertical position along each side of the trailer. These systems have proven very difficult to completely seal the contents of the trailer inside the trailer. Some such systems require a heavy torque tube to run the entire length of the trailer in order to cause the back arms to flip the tarp, making the system heavy, thus reducing payload.
In addition, side rolling tarp systems have been used. A typical side roll tarping system generally includes a roll pipe connected to a tarp. The roll pipe turns in one direction, and travels across the container from one side to the other, as it rolls up the tarp to expose the open container below. To cover the open container, the roll ripe turns in the opposite direction and travels back across the container, thus unrolling the tarp over the open container.
Several disadvantages exist with such conventional side roll systems. Some such systems employ a spring biasing member to apply a load to a pivoting arm for use in rolling and unrolling the tarp. Such systems can be expensive and require a great deal of torque from biasing means, such as for example, large springs, to apply an adequate amount of tension to the tarp. Large mounting brackets are then required to house and store the energy from these biasing members. Further, such systems often employ the use of an arm disposed in the back of a container, which can hamper the operation of a rear door. Additional rolling tarp systems may use a cable or other tensioning device to bring the tarp back over the load. However, such systems using a cable to bring the tarp back over the load may be prone to damage from various loading processes, such as for example, damage from front loaders. Furthermore, when a side roll system is mechanically driven, failure of an actuator can cause the need for manual operation of the system or cause the side roll system to be inoperable until repaired. Furthermore, if a manual bypass is provided for the manual operation of the roll system in the case of a mechanical failure, an operator is often required to climb up near the drive mechanism of the unit to uncouple the actuator. Next, the operator must climb up again to connect the manual crank and lock it in place to work properly, which may be inconvenient or difficult.